1. Field of the Invention
The invention relates to a wireless device having preferred antenna characteristic and a method for improving antenna characteristic of the wireless device. More specifically, a method for increasing ground dimension of an antenna element and a printed circuit board to improve antenna characteristic of the wireless device.
2. The Related Art
According to the progress of the communication technology, the key development is the transfer from wired to wireless communication, such as the popularization of the wireless household phones, mobile phones and personal digital assistants. In the field of wireless communication, the signal is carriered through invisible electromagnetic wave. Therefore, the bridge between electrical signal and electromagnetic wave is an antenna. So the antenna is certainly needed by a wireless device to transmit or receive electromagnetic wave. The antenna is therefore an essential component in the wireless device.
Recently, the wireless device is required to be compact, light, and multi-functional according to a recent demand. The antenna, printed circuit boards and electric components built on the printed circuit boards become smaller and more multi-functional in order to satisfy the above requirement. Due to the above requirement, the wireless device has a great denseness in arrangement of the electric components. Therefore, coupling effect between the electric components is accordingly raised.
Please refer to FIG. 7. A conventional wireless device 900 has a shielding housing 90 and an insulation housing 91 coupled to the shielding housing 90 for receiving a printed circuit board 92 and an antenna 94. The printed circuit board 92 has plurality of electric components (not shown in figures). Also, a wireless processor 93 is arranged on the printed circuit board 92.
The antenna 94 with a ground point 95 and a feeding point 96 is arranged close to the surface of the printed circuit board 92. The ground point 95 and the feeding point 96 of the antenna 94 electronically couple with ground and the wireless processor 93 of the printed circuit board 92 respectively. Therefore, the wireless device 900 transmits and receives electromagnetic wave through the antenna 94, and processes signal carried by electromagnetic wave through the wireless processor 93.
Due to the antenna 94 being arranged close to the surface of the printed circuit board 92, coupling effect between the electric components interferes antenna characteristic of the antenna 94, such as impedance, antenna gain and frequency range. Therefore, the antenna gain of the antenna 94 is decreased and impedance of the antenna 94 becomes worst.